In the 1960s, surveys of Florida's alligator population indicated that

Correct option A

Cause: In the 1960s, surveys of Florida's alligator population indicated that the population was dwindling rapidly.
Action Hunting alligators was banned.
Effect By the early 1990s, the alligator population had recovered, and restricted hunting was allowed.
Outcome: Over the course of the 1990s, reports of alligators appearing on golf courses and lawns increased dramatically.
Conclusion: Therefore, in spite of whatever alligator hunting went on, the alligator population must have increased significantly over the decade of the 1990s.
Argument: Alligator population increased?

Which of the following, if true, most seriously weakens the argument?

A. The human population of Florida increased significantly during the 1990s.
Correct: Weaken,
Earlier - Population of human (x) : population of alligator : (Y)
Now – Population (x+1) : Population of alligator (y) (as population was brought in control, mention in passage)
Increase in the human population more alligator visible compared to earlier less population
Hence more visibility

B. The hunting restrictions applied to commercial as well as private hunters.
Flaw: if restriction were applied, hunting will be limited, this is completely opposite to what is stated in the passage post 1990, this means there was no restriction on hunting, and this strengthen the argument

C. The number of sightings of alligators in lakes and swamps increased greatly in Florida during the 1990s.
Flaw: this strengthens the argument, number of sighting has increased

D. Throughout the 1990s, selling alligator products was more strictly regulated than hunting was.
Flaw: selling product is out of scope of passage and not related to sighting by people

E. Most of the sightings of alligators on golf courses and lawns in the 1990s occurred at times at which few people were present on those golf courses and lawns.
Flaw: this stem, though says most of the alligator sighted but also indicates by few people, which make the stem contrast, this stem only supports conclusion with additional information and doesn’t weaken the argument

https://gmatclub.com/forum/farmer-sever ... 94365.html
in the above question, we have questioned the credibility of the finding by saying no one was present while they saw the lion.
But in this question, we were told not to question the finding(option E). Would you please explain the conundrum? GMATNinjaTwo, GMATNinja,

Hello, Manoj1998, and pardon the interruption, since I am not a GMAT Ninja. However, I have posted several responses in this thread, and I have even written a post on the very question you ask, way back on page 1, here. I hope it proves helpful to you and resolves your doubts.

Good luck with your studies.

- Andrew

We are told "not to question the finding." We are told people would not DELIBERATELY file a false report.

This question is asking us to pinpoint the assumption that must fill the gap between "People CLAIM to see a mountain lion" and "people ACTUALLY SAW a mountain lying."

We do not doubt that people CLAIMED TO SEE the mountain lion, and we do not doubt that they GENUINELY BELIEVE they saw the mountain lion, but there's still a gap between that and ACTUALLY SEEING a mountain lion. Maybe they were mistaken. Maybe their eyes played tricks on them. Maybe they saw a different animal and mistook it for a mountain lion.

It would help if a sighting had more than one person involved, to corroborate that it was in fact a mountain lion. C points out that actually many sightings were people alone. This is, to be clear, one of the *weakest* weakeners I've ever seen! But it barely blows the feather in the direction of 'the argument is weaker' and that's all we have to do.

E is not relevant. E says 'most people never said they saw a mountain lion,' which might be true. But the passage makes clear people in that last few months have claimed to see one, even though mountain lions had believed to be driven away 20 years ago. Sure MOST people haven't seen one, but that doesn't weaken the fact that many people *have* in recent months.

IanStewart AndrewN GMATNinja

So the core of your argument is:

The more people are around -> the higher the probability that an alligator is seen on a lawn or golf course -> the higher the report rate, even though real amount of alligators is equal to or less than before the relevant time frame

What if there are more people AND more alligators?

Applying the logic you explain the answer with, I would still get the same result: An increase in the amount of reports, but maybe, I also have an increase in the aligator population

This is just my opinion, but I am a little frustrated with these questions where likelihoods start popping into the equation...

Hello, hadimadi. You will note that no one you mentioned above disputes the notion that the alligator population could have increased. The goal is to weaken the argument that the alligator population must have increased significantly (my italics). In fact, I made it a point to draw attention to the distinction in my original post:


Neither does IanStewart dismiss the possibility that the alligator population has increased (my highlights):


And finally, GMATNinja had his say on the matter a little further down on the first page. Notice the consistent message (again, my highlights):


You have to be careful not to confuse a weaken question with a made-up stem that asks you for irrefutable evidence against an argument. We are only looking to weaken the must here, not necessarily the content of the argument itself.

I suspect that this question frustrates a lot of people. Once that frustration wears off, however, you can really dig into the question stem and see the task a little differently, the answer choices for what they are, and you can begin to see other challenging CR weaken questions the same way.

Good luck with your studies.

- Andrew

AndrewN

Hi Andrew,

thanks for taking the time and rereading everyone's posts (which I apparently didn't do in detail).

I think I know understand:

There could be more people and more alligators, but it must not be true that there are more alligators in the scenario that population increased (it could be, however), because we assume that more people -> likely more reports

Then, I still have to cope with this likelihood thing...

Thanks Andrew

Hello again, hadimadi. Glad to help. There is just one clarification I would like to make. We are not assuming that more people means more reports. There is no assumption to be made. The emphasis should be more on likely: the more people there are to see something, the more likely it is that reports would increase. Yes, you still have to consider likelihoods, but weaken questions are designed with a scale of likelihood in mind. The answer choice that most weakens the argument is the one to choose. On easier questions, there might be one option that we assess at a 99 percent likelihood of weakening the argument, but this question is unassuming, and the task becomes more challenging.

- Andrew

I want to share some of my thoughts for the option (A) and (E). The former was not an obvious winner to me when I did this question the first time, while the latter was tempting because it resembled the correct answer to the "mountain lion" CR question.

Premise: Over the course of the 1990s, reports of alligators appearing on golf courses and lawns increased dramatically.

Conclusion: Therefore, in spite of whatever alligator hunting went on, the alligator population must have increased significantly over the decade of the 1990s.

Let's check the option (A):
A. The human population of Florida increased significantly during the 1990s.

Several experts have pointed out that if the human population increased significantly, it is likely that at least some sightings occurred because there are more people around to see the alligators. I can understand this line of thinking, but I have to say that the connection is not very persuasive because of the modifier "reports of alligators appearing on golf courses and lawns." They are not reports of sighting in rivers or lakes, places anyone can be, but reports of sighting at golf lawns, places where only the member of golf clubs can be.

Maybe in some places in the US, it is reasonable to infer that the rise in human population would likely lead to a rise in the number of golf players, but that is not the case in most Asian countries (in my opinion). Here, the rise in human population would likely lead to growths in the number of new buildings or the number of gym customers, but golf players? Not really....

I do not reject (A), though. As some experts have pointes out, the option (A) could be two-pronged. Even though I dislike the connection mentioned above, I could understand that a significant growth in human population usually triggers environmental disruption and thus some alligators' habitats might have been destroyed. So, it is possible that the alligators were displaced and entered the golf areas, or it could be the case that the alligators never left the river they stay but their habitats were just turned into golf lawns.

Let's check the option (E):
E. Most of the sightings of alligators on golf courses and lawns in the 1990s occurred at times at which few people were present on those golf courses and lawns.

This is similar to the correct answer of the mountain lion question but is the incorrect answer to this one......perhaps the GMAC was trying to prove its diversity and creativity when making this question.

The option (E), while tempting, is incorrect for two reasons:
(1) It says "few people," compared with a single person in the mountain lion quesiton. Even if we apply the logic in the mountain lion question that the others can help correct the mistaken belief, it does not work here. There were "few people" in most of the sightings, so if one of them were to mistakenly believe that he or she saw an alligator, the others could help correct the mistaken belief. So, we cannot really use the logic in the mountain lion case to doubt the accuracy of the reports in this alligator case.

(2) Alright, even if we decide to ignore the logic in the mountain lion case and make our own assumption that few people can be mistaken together about what they see (after all, it is not a crazy assumption), the option (E) might be able to suggest the accuracy of most of the reports is doubtful.

But, the premise says that "reports of alligators...... increased dramatically." The modifier "dramatically" plays a role here. The word "dramatically" means double-digit growth or even rise of multiple times.

Let's say that there were 100 reports before and the number of reports grew to 150 (at least) in the 1990s. Even if we take an extreme move, thinking that most of the sightings, or 80 to 90, were false or mistaken, there were still many reports of sightings in which many people were present. These reports should be more likely accurate. Now, the option (E) could not attack the accuracy of these reports. And these reports could still support the conclusion that the alligator population have increased.

You've thought through the question well, but I think you may have distorted the meaning of one important phrase, and that may have made the right answer seem less convincing. When the question talks about "golf courses and lawns", it is talking about two different things, but I think you combined them into a single thing, "golf lawns". When the question talks about "lawns", it's talking about the stretches of grass in front or in back of people's houses. So it's not only golfers who were seeing the alligators; it was homeowners too. I agree that if it was only golfers seeing alligators, we'd have to look at the question differently, because, as you correctly point out, we can't conclude there will be more golfers just because the population goes up, among other reasons.

Thank you IanStewart so much for pointing this out--now the option (A) is more persuasive to me! If it is "golf courses" and "lawns" where the alligators were reported to have appear, the link between more reports and higher human population will be more obvious to me. The rise in the number of reports of sighting of alligators on lawns could still be attributed to a growth in alligator population, but as anyone can be on the lawns, it could also be attributed to the rise in the number of residents or citizens! The latter attribution would weaken the conclusion.

I had a problem understanding WHY C was not a right answer.

C. The number of sightings of alligators in lakes and swamps increased greatly in Florida during the 1990s. - It's a great trap answer because it uses similar wording of the passage. The passage says that alligators appear on golf courses and lawns "Over the course of the 1990s, reports of alligators appearing on golf courses and lawns increased dramatically." Answer C strengthens the conclusion by adding additional information that the alligators also appear on lakes and swamps. Now there are alligators in two additional places. Therefore, number of alligators must have been increased if they appear in other places as well.

Answer A is very unusual correct answer. You can only locate it if you eliminate wrong answer choices first. A. The human population of Florida increased significantly during the 1990s. - Perhaps the amount of alligators are still same but the amount of people have increased. If there were 20 people on the golf course before who saw 5 alligators (let's say 20 sighting), now there are 40 person who saw 5 alligators (now: 40 sighting). Therefore the number people, and thus the number of sightings have increased not the number of alligators.

Also note that, trap answer C starts with wording "The number of sightings" to trap you to think that it is correct choice. If you don't pay good attention to the additional information it adds to conclusion you end up picking C over A. In answer choice A the number of sighting increased must be inferred.

A. The human population of Florida increased significantly during the 1990s. Hold
B. The hunting restrictions applied to commercial as well as private hunters. No impact on the argument so eliminate
C. The number of sightings of alligators in lakes and swamps increased greatly in Florida during the 1990s. Strengthens the argument therefore eliminate
D. Throughout the 1990s, selling alligator products was more strictly regulated than hunting was. No impact on the argument so eliminate
E. Most of the sightings of alligators on golf courses and lawns in the 1990s occurred at times at which few people were present on those golf courses and lawns. Now few people were present that means more than one was present meaning thereby that the sightings reported are true. if sightings reported are true that means the population of the alligators have increased. this at best strengthens the argument.
Therefore option A is the answer

Dear experts,

I read almost comments. However, I am sill unconvinced.

I can eliminate (B), (C), and (D). I am still struggling with (A) and (E).

Here are my thought.
First, if possible we should link the evidence/premise to the conclusion as much as possible.

We got reports of alligators on golf courses and lawns. --> The alligator population must have increased significantly

(A) The human population of Florida increased..
> The more population, The more report (OK)
> The more population, The more hunt (?)

(E) Most of the sightings of alligators on golf courses and lawns in the 1990s occurred at times at which few people were present on those golf courses and lawns.

few people were present on those golf ---> few people reported the sightings of alligators. ---> other few people also reported the sightings of alligators, and those alligators may be the same alligators that the first few people reported. Thus, the population of alligators haven't increased. It is just an increasing number of report.

(E) does connect between the provided premise and the provided conclusion. But (A) needs some more thought. It seems that it depends on how we interpret the choices... (for this question)

PS. I did read almost comments.

I need to understand your reasoning for E a little better. If there are *few* people on the lawns and golf courses, the chance of a "duplicate sighting" is *low*, but your reasoning seems to imply that it's likely. "few" means 'not very many.' If sightings happen when there aren't many people out, and if there are more sightings reported, that means it's unlikely to have a lot of duplicate sightings of the same alligator at the same time, so it's more likely that there are more alligators around.

Consider if the sightings occurred when there were MANY people on the lawns and golf courses. Well then that would mean that most likely, a bunch of people are reporting the same gator. So *that* would weaken the argument.

ReedArnoldMPREP


For (E), I imply that few = not very many. (please, correct if I am wrong : Actually I am not sure whether "few" = "a few" or not.)
Supposed that few = not very many, what I mean is that if few people, let's say 5 people, on the lawns and golf courses saw alligators, then they reported that they had seen alligators. On the next day, other few people, 3 people, saw the same alligators. Then, these 2-3 people reported again. Thus, total 8 people saw the same alligators, but there are 2 reports. Thus, it does weaken the conclusion because there are many reports rather than many alligators.

First off, *we* can't say that these people are probably seeing the same alligators. And the fact that there are *very few* people on the courses/lawns doesn't affect the question about whether they're seeing the *same alligators* on different days. If there are many people, or only few people, each group could see the same alligators on different days and make their reports. The number of people doesn't justify the jump to "Oh so it's probably the same gators they're seeing").

(NOTE: if there are MANY people on the lawns/courses during these sightings, then the reports THAT DAY are more likely duplicate sightings of the same alligator! So that WOULD weaken this argument).

While it's certainly possible that--and it would certainly weaken the argument if--all these reports are actually of the same alligators, **Answer choice E doesn't actually indicate this**. The fact that there are few people on the lawns/golf courses tells me nothing about whether these few people are seeing the same gators, day after day.... It just says there aren't many people on the golf courses/lawns when the gator sightings that get reported happen. You're making the leap to say "Oh, well, this implies that maybe they're seeing the same gators day after day!" But... maybe they aren't? Maybe these few people are seeing different gators day in day out? Heck if I know, so I don't see why the small number of people matters. This answer gives us no reason to think either is happening, so it doesn't weaken the argument.

If *anything*, the fact that there aren't many people out when these sightings are recorded STRENGTHENS the argument, because it tells me each sighting probably isn't 'duplicated' much.

And remember, you need to answer...why are reports of alligator sightings increasing so much? That's what's at heart of this question. The author has decided "More gator sightings" probably means "more gators," it's our job to ask, "How could there be more gator sightings but NOT more gators?" Answer choice E does not sufficiently explain that phenomenon. But if there are just MORE PEOPLE, there are more people who can report any gators they see.

Here's the other question to ask about this 'what if they're seeing the same gators, day in day out?' **Why are the number of reports increasing?** Why didn't people USED to see the same gators day in and day out and make similar numbers of reports?

Why would gator reports go up? Let's consider that. Either:

There are in fact more gators being seeing now.

There are not more gators, but people are more likely to make a report when they see a gator.

There are not more gators, but there are more people who see gators.

There are not more gators, but people are making a bunch of mistaken reports.

If people are seeing the same gators day in/day out, why are there MORE REPORTS now? Did they used to NOT report seeing the same gators day in, day out?